Sen. Lindsey Graham is on a mission to convince Republican presidential hopefuls to stop ignoring national security, traditionally a key issue in the South Carolina primary but one that is likely to be eclipsed by the economy this time around.

Graham's crusade could get a boost from a scheduled Nov. 15 GOP presidential primary debate that is set to focus solely on foreign policy and national defense. And the South Carolina Republican said Texas Gov. Rick Perry, former Massachusetts Gov. Mitt Romney and former Sen. Rick Santorum (Pa.) have all begun to give foreign policy issues more attention lately.

But Graham remains dissatisfied and warned that overlooking international affairs could carry a high political price.

In a brief telephone interview with Roll Call, Graham said the Republican White House field "would be wise to talk about" national security, saying the typically important issue "is ripe for the taking" and could elevate a candidate's prospects in his early primary state. Graham said the Republican presidential hopefuls need to "make distinctions" between their approaches to foreign policy and national defense, and that of President Barack Obama.

"This is a big part of being president," Graham said. "Our candidates for president need to challenge him."

The issues have taken on more salience given Obama's recent foreign policy and national security successes, from killing al-Qaida leader Osama bin Laden to supporting Libyan rebels as they ousted Moammar Gadhafi. Recent polls have shown that Obama's favorability has increased since Gadhafi's demise and the president's decision to pull American troops out of Iraq by year's end. Both the Libya and Iraq strategies have angered many of the GOP faithful, including Graham.

He said last week that the top tier of the Republican White House field has made strides in its discussions of national security. "It's not what I would like, but it's heading in the right direction," he said. But in an interview on "Fox News Sunday" a few days before Graham spoke with Roll Call, South Carolina's senior Senator said the reason he accepted the Sunday interview request was to push the candidates to home in on foreign policy and national defense. Graham indicated that he was concerned about the support expressed in some quarters of the GOP for pulling out of Afghanistan and Iraq independent of victory, suggesting that such positions hewed too closely to Obama's strategy.

Graham said that the candidates' focus on Iraq, the prison at Guant&aacute;namo Bay, Cuba, Iran and nuclear weapons, the terrorist threat and Israel thus far "has not been robust enough." He did, however, compliment Santorum for providing "the closest thing we have to a Ronald Reagan voice." Former Utah Gov. Jon Huntsman, who resigned earlier this year as Obama's ambassador to China, has been among the most ardent advocates of paring down U.S. military commitments abroad.

Graham called Huntsman a friend, but he said "that's not a road that leads to victory with South Carolina primary voters."

"If I hear a Republican nominee embracing leading from behind, they will have a very difficult time in South Carolina," Graham said on "Fox News Sunday." "The issues that I'm talking about: Iran having a nuclear weapon — a nation without a viable jail on the war on terror, Iraq now being compromised, Afghanistan being compromised, our best friend in Israel feeling they can't trust us — all these issues are worth more discussion on our side."

But not all South Carolina Republicans agree that a candidate's national security positions will influence voters as it has in past years.

The nation's struggling economy, which has been felt in the Palmetto State, has had a significant effect on how South Carolinians are viewing the 2012 elections. In parts of the state where social issues or national security might dominate, the economy has been at the fore of voters' concerns, a dynamic that shows no signs of abating according to many state political operatives.

National security tends to be most influential among Republicans who live near and along the Atlantic coast, as well as in the lowcountry region that encompasses Charleston. Even there, however, it's all about the economy, said Rep. Tim Scott, a freshman Republican from Charleston, whose district also includes Myrtle Beach. National security is "always important," he said in an interview. "But overshadowing all issues is the jobs situation. Between now and the primary, that won't change."

Scott, who won his seat last year on the strength of tea party support, has been holding town hall meetings with the Republican presidential candidates. Next on his schedule are events with Santorum and former Speaker Newt Gingrich. (Ga.). Scott referred to new frontrunner Herman Cain, a Georgia businessman and talk-show host, as the "hottest ticket in the party right now." Romney, Scott added, has been "consistent."

Graham, an Air Force reservist, is a leading Republican voice in the Senate on national security. A hawk, he is closely aligned with Senate Armed Services ranking member John McCain (R-Ariz.), whom he staunchly supported for president in 2008. McCain won South Carolina's primary that year on his way to securing the GOP nomination. Graham has yet to endorse a candidate in the 2012 contest.

Though Graham's opinions carry some weight, Sen. Jim DeMint has emerged as the state's most influential elected Republican over the past few years. He has helped boost conservative Senate candidates running in other states through his Senate Conservatives Fund political action committee, while shaping opinion on fiscal issues inside and outside the Palmetto State. DeMint's outlook on national security is similar to Graham's, but his focus in the presidential primary has been on the economy and the candidates' positions on related issues.

At least one South Carolina Republican sides with Graham that national security will play its typically significant role in the primary. State Rep. Phyllis Henderson, who has not endorsed a candidate, said Obama's decision to pull all troops from Iraq could reignite foreign policy and national defense as major campaign issues.

Henderson said it remains unclear whether Republican voters will take the hawkish view, as they have in the past, or if the stagnant economy and high federal deficit will create support for military retrenchment. "If Republicans try to say we shouldn't leave Iraq, I think there's a lot of hardcore Republican primary voters" who might disagree, she said.